Methods and apparatuses for joining sheet formed members together, thereby producing leak proof or non-leak proof joints, are well known in the prior art.
A joint of this type could be made by means of drawing said sheet formed members into a cup-shaped or protruding portion having a cylindrical or slightly conical side wall and a bottom wall and subsequently compressing said bottom wall creating a lateral extrusion of the same thereby forming a laterally enlarged shape which mechanically interlocks the sheet formed members. This technique is usually referred to as clinching in the art.
The methods and tools according to the prior art make use of the well known one or two step principles. In the one step method the whole procedure for making the joint takes place during one single relative movement between a punch and a co-operating die and anvil. In a two step method the final compression of the material takes place during a second squeezing operation outside the die cavity.
A suitable tool comprises generally two separate tool parts, which co-operate for producing said joint. A first tool part has the form of a punch which in a linear movement is driven in the direction of a co-axial second tool part in the form of a die with a die cavity at the bottom of which an anvil is arranged.
For making the joint the sheet formed members are usually positioned against, and resting on, the second tool part, the die, which could be provided with movable die elements arranged in certain embodiments sliding laterally on a support surface against the forces from a spring element. The spring element is generally constituted by a ring made of an elastomer or a toroid formed metal spring surrounding the movable die elements.
When gluing sheet formed material together the combination with clinching is very useful for fixing the work pieces together in predefined relative positions before the adhesive is cured.
However, when making a clinch joint between two work pieces positioned on top of each other with an intermediate layer of viscous, not yet cured, adhesive, excessive adhesive in the area where the clinch joint is to be made will be detrimental to the quality of the joint.
Therefore, before the actual joining process starts adhesive has to be locally removed from the area of the intended joint.